Explicit rate flow control for ABR services in ATM networks

Abstract

We propose a novel explicit rate flow control algorithm intended for available-bit-rate (ABR) service on an ATM network subject to loss and fairness constraints. The goal is to guarantee low cell loss in order to avoid throughput collapse due to retransmission by higher level protocols. The mechanism draws on measuring the current queue length and bandwidth availability, as well as tracking the current number of active sessions contending for capacity, to adjust an explicit bound on the source transmission rates. We identify the factors that affect queue overflows and propose simple design rules aimed at achieving transmission with controlled loss in a dynamic environment. We also discuss how conservative design rules might be relaxed by accounting for statistical multiplexing in bandwidth sharing among bursty ABR sources and variable-bit-rate (VBR) sources.